Rehydration apparatus

ABSTRACT

Apparatus for continuous rehydration of material, typically freeze dried shrimp, in which helically arranged conduit means, rotated about the axis of the helix, is employed to establish successive treating zones, including at least a rehydrating zone and a dewatering zone, and cyclically operating feed means is used to supply successive quantities of dried material and liquid rehydration medium to the input end of the conduit means, the rotating helical conduit means operating to advance the successive quantities continuously to accomplish, e.g., saturation, dewatering, and equilibration.

United States Patent 119] Stevenson, III

1451 Sept. 25, 1973 REHYDRATION APPARATUS [76] Inventor: William H. Stevenson, Ill, c/o Ocean Trove Development Corp., PO. Box 1 1565, Winston-Salem, NC. 27106 22 Filed: June 8,1971

21 Appl. No.: 151,063

52] us. 01. 99/536 [51 1m. c1 A23l1/33 [58] Field of Search 99/234 R, 443 C,

99/111, 536; 259/DlG-..24, 3, 81, 89, 90

[56] 7 References Cited UNITED STATES PATENTS 3,586,510 6/1 97l Farkas et al. 99/237 R X 2,263,] 18 11/1941 Carney 259/8- Primary Examiner-John Petrakes Assistant Examiner-Alan l. Cantor Attorney-Roylance, Abrams, Berdo and Kaul [5 7] ABSTRACT Apparatus for continuous rehydration of material, typi-- cally freeze dried shrimp, in which helically arranged conduit means, rotated about the axis of the helix, is employed to establish successive treating zones, including at lea'sta rehydrating zone and a dewatering zone, and cyclically operating feed means is used to supply successivequantities of dried material and liquid rehydration medium to the input end of the conduit means, the rotating helical conduit means operating to advance the successive quantitiesjcontinuously to accomplish, ve.g., saturation, dewatering, and equilibration.

14 Claims, 20 Drawing Figures RECOVERED SOLIDS PATENTEDSEPZSISH $760,716

SHEET-'2 BF 8 FIG. 2

PATENIEI] 39255473 SHEET B (If 8 FIG 9A FIG. 9

FIG. 104

FIG. 10

FIG. 106' FIG. 10B

PATENIEI] SEPZS I975 SHEET 7 0F 8 Q m F FIG. 11

/ I I I I I I l I I ll PAIENIEDSEPZSISH saw a or 8 DRIED MATERIAL FEED MEANS 1 REHYDRATION APPARATUS RELATED APPLICATION Apparatus according to the invention is particularly useful in practicing the rehydration method disclosed and claimed in my copending application Ser. No. 151,062, filed concurrently herewith.

"This invention relates to apparatus for continuously rehydrating dried material and, more particularly, to such apparatus capable of passing the dried material continuously through at least two zones in succession, typically through a first zone for introduction of water into the material, and then through a second zone to separate the material from residual water and commence equilibration. While generally useful for rehydration of dried materials of any kind which are normally presented in the form of pieces, the invention is particularly advantageous for rehydrating foodstuffs such as shrimp.

BACKGROUND OF THE INVENTION In a number of fields, it is highly desirable to dry materials in order to reduce shipping costs. This is particularly true of food materials such as shrimp since, with such materials, drying affects not only removal of water, and thereby greatly reduces the weight of the material, but also conversion of the material to a condition in which the material can be stored for prolonged periods at normal temperatures without spoilage. It has long been recognized that various drying procedures are effective and relatively economical so that, e.g., shrimp can be harvested in a geographic area distant from the market to be served, the dried shrimp then being shipped without refrigeration or other expensive procedures otherwise necessary to prevent spoilage. In particular fields, however, the advantages of drying the material have not been capitalized upon, primarily because there has heretofore been no practical way to reconstitute the dried material so that it is presented to the market in an acceptable usable form approximating freshness. While rehydration has been accomplished on a small lotbasis, as in laboratory investigations and limited home use, there has simply been no commercially practical apparatus available for large scale rehydration of dried products such as shrimp.

One reason for failure of such apparatus to become available has been the fact that it is not satisfactory simply to put water back into the dried product. Rather, the water must be both introduced into the dried product and then caused to distribute through the product so that, in the finished material, the water is present in essentially the same fashion as it existed in the original material. Broadly considered, satisfactory rehydration can be accomplished only if the dried material is first substantially saturated with water, and the saturated material then recovered and maintained under conditions such that the water introduced will redistribute through the product in a manner which can be termed equilibration. While this succession of steps can be carried out on a small basis, using stationary vessels in a batch operation, commercially practical means for accomplishing the steps continuouslyin sequencehas not heretofore been proposed.

OBJECTS OF THE INVENTION A general object of the invention is to provide apparatus capable of continuously passing a dried material through successive zones in a fashion such that introduction of water into the dried material can be accomplished in a first zone, and that conditions suitable for equilibration can be maintained in a second zone.

Another object is to provide a continuously operating apparatus capable of rehydrating dried materials, typically shrimp, in such fashion as to convert the material to a condition approximating that which existed prior to drying.

A further object is to provide such an apparatus capable of presenting the dry material in evacuated form while in contact with the rehydration liquid.

Yet another object is to devise such an apparatus wherein the material being treated is passed through successive zones defined by a continuous tubular structure, so that the problems inherent in transferring material from one vessel or chamber to another separate vessel or chamber are avoided.

A still further object is to devise such an apparatus wherein feeding of the material to be rehydrated is accomplished in automatic fashion without requiring use of such extraneous devices as material pumps or star valves.

SUMMARY OF THE INVENTION Generally stated, apparatus according to the invention is characterized by use of helically arranged conduit means to define the successive treating zones, the conduit means being supported for rotation about the axis of the helix, feed means being employed to supply rehydration liquid and dried material in successive quantities each accommodated by a different convolution of the helix.

In order that the manner in which the foregoing and other objects are attained in accordance with the invention can be understood in detail, particularly advantageous embodiments thereof will be described with reference to the accompanying drawings, which form a part of the original disclosure of this application, and wherein:

FIG. 1 is a semidiagrammatic perspective view of an apparatus according to one embodiment of the invention;

FIG. 2 is a side elevational view of one end portion of the apparatus of FIG. 1, with portions broken away for clarity;

FIG. 3 is a view similar to FIG. 2 of the opposite end of the apparatus;

FIG. 4 is an end elevational view taken generally on line 4-4, FIG. 2;

FIG. 5 is an end elevational view taken generally on line 5-5, FIG. 3;

FIG. 6 is a side elevational view of a support drum forming part of the apparatus of FIG. 1;

FIG. 7 is a side elevational view of a helical conduit and supporting structure therefor which form part of the apparatus of FIG. 1;

FIG. 8 is a fragmentary transverse sectional view taken on line 8--8, FIG. 2;

FIGS. 9 and 9A are semidiagrammatic views showing sequential positions of the first half convolution of an outer conduit of the apparatus of FIG. 1 during operation thereof;

FIGS. 10l0C are semidiagrammatic views illustrating the manner in which the material being rehydrated is transferred from an outer conduit to an inner conduit during operation of the apparatus of FIG. 1;

FIG. 11 is a view; partly in vertical section and partly in side elevation, of an infeed portion of the apparatus of FIG. 1;

FIG. 12 is a semidiagrammatic view of a portion of the apparatus of FIG. 1 showing the operating condi-' tion thereof immediately after one cycle of the feeding operation;

FIG. 13 is a longitudinal sectional view of a portion of an inner conduit equipped with a sonic energy generator and forming part of the apparatus of FIG. 1;

FIG. 14 is a fragmentary longitudinal sectional view illustrating a portion of the apparatus of FIGS. 2 and 3 modified for evacuation of the outer conduit;

FIG. 15 is a fragmentary view, similar to FIG. 14, showing a modified form of inner conduit useful in the apparatus of FIG. 1; and

FIG. 16 is a semidiagrammatic side elevational view of an apparatus according to another embodiment of the invention.

THE EMBODIMENT OF FIGS. 1-12 Referring now to the drawings in detail, and first to FIG. 1, the illustrated embodiment of the apparatus comprises a material feeding means, indicated generally at 1, a rotary rehydration, dewatering and equilibration unit, indicated generally at 2, an off-bearing conveyor 3 disposed to receive the rehydrated product, and liquid recycle means comprising the liquid receiver 4, centrifuges 5 and 5a arranged in series, make-up tank 6, pump 7, and heat exchanger 8.

Unit 2 comprises a first conduit 9, which defines the rehydration zone, and a second tube 10, which defines both a water removal zone and an equilibration zone. Conduits 9 and 10 are arranged in generally helical fashion and are both carried by a cylindrical drum 11 which is supported for rotation about a generally horizontal axis, as will be hereinafter described.

Conduit 9 includes a straight input portion 12 located at the center of drum 1 1 and coaxial with the axis of rotation of the drum. From end portion 12, conduit 9 extends outwardly, through an opening 13 in the wall of drum 11, and thence helically about the drum. At the opposite end of the drum, the discharge end portion 14 of conduit 9 extends inwardly, passing through an opening 15 in the drum, in such fashion that discharge end portion 14 terminates within the drum and lies immediately adjacent the inner surface of the wall of the drum.

The second conduit 10 is disposed within drum l1 and includes an input end portion 16 which is connected to discharge end portion 14 of conduit 9 by a conventional fluid-tight releasable coupling 17, FIG. 5. From its input end portion 16, conduit 10 extends helically through drum ll, terminating in a discharge end portion 18 which is bent out of the helix of the main portion of conduit 10 in such fashion as to extend out of the same end of drum 1 l at which the input end portion 12 of conduit 9 is located. As will be clear from FIG. 2, discharge end portion 18 of conduit 10 passes immediately adjacent the end of the wall of the drum and projects therebeyond to a position above the product conveyor 3. Product conveyor 3 includes an endless horizontal belt disposed to travel transversely relative to the drum.

As will be understood from a comparison of FIGS. 2 and 6, end portion 19 of drum 11 is substantially thicker than the remainder of the wall of the drum. End

portion 19 is provided with a circular series of longitudinally extending slots 20 which are of sufficient length and width and are of sufficient number to assure that, in any rotational position of the drum, the slots 20 in the downwardly disposed portion of the drum will accommodate a substantial liquid flow. The series of slots 20 is spaced from the adjacent end of the drum by an unbroken wall portion, and this end portion of the drum is completed by a transverse annular outwardly projecting bearing flange 21.

A similar bearing flange 22 is provided at the opposite end of drum 11 and is formed with gear teeth 23, FIGS. 5 and 6. Over the major portion of its length, lying between flange 22 and the end 24 of the thickened wall portion, the drum is provided with a plurality of longitudinally extending, outwardly projecting stiffening strips 25 each having a series of arcuate notches 26. As will be seen in FIG. 2, the convolutions of conduit 9 extend along and are directly seated in the notches 26. Thus, the strips 25 serve both to strengthen the drum and to locate and support the conduit 9.

The inner surface of the wall of drum 1] is right cylindrical, unbroken save by the slots 20. An annular member 27, FIG. 2, is secured to the inner surface of the wall of the drum in transverse fashion and includes a flange 28 which projects inwardly of the drum immediately adjacent the ends of slots 20 which are nearer bearing flange 21. The end of the drum at bearing flange 21 is completely open. At the opposite end, a closure plate 29, FIG. 1, is provided, both to retain liquid in the lower portion of the drum, as later described, and to provide additional strength.

Drum 11 can be fabricated from rigid polymeric material with bearing flanges 21 and 22, including gear teeth 23, integral with the body of the drum.

The drum is arranged for rotation about an axis which is inclined at a small angle a, FIG. 1, downwardly toward the end of the drum defined by bearing flange 21. The helices defined by conduits 9 and 10 are coaxial and the common axis of the helices is coincident with the axis of rotation of drum 11.

The combination of the drum and conduits is supported by roller stands indicated generally at 30 and 31. Roller stand 30 includes an upright frame plate 32 lying in a plane transverse to the axis of rotation of the drum, three strengthening plates 33 extending at right angles to plate 32 and an additional plate 34 which is parallel to plate 32, spaced therefrom, and secured rigidly to plates 33. The upper edge 35 of main plate 32 is arcuate, with a radius of curvature substantially the same as that of the inner surface of the wall of drum 1 1. The upper edge of plate 34 is also arcuate, but with a radius of curvature slightly greater than that of the outer surface of bearing flange 21. Three support rollers 37 are provided, each supported for free rotation by a shaft 38 extending through and fixed to plates 32and 34. Rollers 37 are identical, including a first end flange 39, of larger diameter, a main right cylindrical roller body 40, and a right cylindrical end flange 41 of a diameter intermediate that of portion 40 and flange 39. The dimensions of rollers 37, and their locations established by frame plates 32-34, are such that the bearing flange 21 of drum 11 can be rotatably seated in the eradle afforded by the three rollers 37, with the periphery of flange 21 engaging the surfaces of the main roller bodies 40, and with the periphery of the end flanges 41 of the rollers engaging the outer surface of the drum immediately adjacent to bearing flange'2l. The rollers 37 are advantageously supported on the respective shafts 38 by conventional antifriction roller bearings of a type restraining the rollers against axial movement.

Roller stand 31 similarly comprises a main frame plate 42 which lies in a plane transverse to the axis of rotation of the roller, a plurality of frame plates 43 lying in parallel planes at right angles to plate 42, and a plate 44 lying in a plane parallel to plate 42 and secured rigidly to plates 43. Roller stand 30 includes three rollers 45 each supported by a fixed shaft 46 extending between and secured rigidly to plates 42 and 44. Rollers 45 are identical, including an end flange 47, an intermediate roller portion '48, and an end roller portion 49. v

The frame afforded by plates 42-44 supports rollers 45 in such fashion that, when bearing flange 21 of .drum

1 l is properly seated. on roller stand 30, bearing flange 22 of the drum is received by the combination of rollers 45, flange 22 extending through the space between portions 47 and 49 of rollers 45, with end roller portions 49 in direct rolling engagement with that portion of the outer surface of the wall of the drum which lies immediately adjacent bearing flange 22. The dimensions of rollers 45 are such that, when end roller portions 49 properly engage the drum, the crests of gear teeth 23 are held in, at most, only light engagement with the right cylindrical surface of the intermediate portions 48 of the rollers. As in the roller stand 31, the rollers 45 of roller stand 32 are supported on their respective shafts 46 by conventional antifriction roller bearings of a type restraining the rollers against axial movement.

While frame plates 32 and 42 extend upwardly beyond the ends of drum 11, these plates are spaced, axially of the drum, by a distance somewhat greater than the overall length of the drum. The upper arcuate edge 36 of plate 34 of roller stand 30, and the upper arcuate edge 50 of plate 44 of roller stand 31 are spaced below drum 11. Accordingly, the drum 1 1 is supported for rotation entirely by the rollers 37 and 45, such rotation being free and unimpeded.

Plates 43 of roller stand 31 are interconnected by a horizontal plate 51 which is rigidly attached not only to plates 43 but also to plates 42 and 44, and which lies in a plane beneath the lowermost one of rollers 45. A conventional electric drive motor and speed reduction gearing unit 52 is mounted on plate 51 in such fashion that the output pinion 53 of unit 52 is disposed in meshed, driving engagement with gear teeth 23 of flange 22 of drum 11. Accordingly, when the motor of unit 52 is energized, drum 1 1,, and therefore the combination of helically disposed conduits 9 and 10, are caused to rotate continuously about the common axis established by the rollers 37, 45. Such rotation is at a slow rate of, e.g., from one rotation every several minutes to 3 rpm.

As seen in FIG. 7, the second conduit is supportedby a frame indicated generally at 55 and comprising longitudinally extending bars 56 rigidly secured to and when the combination of frame 55 and conduit 10 is disposed within drum 1 l, the shoes 58 are in flush sliding engagement with the inner surface of the wall of the drum. Frame 55 includes four of the longitudinal bars 56 and each bar 56 is provided with a series of arcuate outwardly opening notches 59 in which conduit 10 is seated.

With conduit 10 arranged in helical fashion and disposed on frame 55 in the manner just described, the combination of frame 55 and conduit 10 can be inserted into drum 11 through the open end of the drum, either through the end at bearing flange 21 or through the opposite end, prior to application of closure 29.

interconnected by cross members 57. Two pairs of the cross members 57 are provided, .with each pair at a different end of frame 55. Cross members 57 extend diametrically with respect to the helix of conduit 10 and are of a length such that the ends of the cross members project beyond the outer diameter of the helix. Each cross member 57 is provided at each of its ends with a shoe 58, the length of members 57 being such that,

During such insertion, the shoes 58 will be in sliding engagement with the wall of the drum and the combination of shoes 58 and cross members 57 will assure that the helix of conduit 10 is maintained concentric with the central axis of the drtlm and, therefore, with the axis of rotation of the rotary unit. When the assembly seen in FIG. 7 has been completely inserted and properly positioned in drum 11, the input end portion 14 of conduit 10 can then be connected, by connector 17, to the discharge end of conduit 9, when the latter is properly assembled on the drum. When cleaning is necessary, the assembly of conduit 10 and frame 55 can be readily removed, after releasing coupling 17. In order to provide for freedom of movement of the combination of conduit 10 and frame 55 relative to the drum, during assembly and disassembly, the internal flange member 27 can be made removable, as by being disposed in a force fit with the wall of the drum.

Conduits 9 and 10 can advantageously be formed of a relatively flexible polymeric material such as polyethylene, for example. Formed of such material, the conduits are capable of being readily wound into helical configuration and unwound so as to lie straight for flushing with a cleaning liquid during cleaning of the apparatus. In this connection, it is to be noted that the combination of conduits 9 and 10 can be made in such fashion that, throughout the total length of the two conduits, the internal surfaces are interrupted only by such perforations or other openings as arenecessary to allow liquid to escape from the conduits in controlled fashion. Accordingly, opportunities for the material being treated to collect on the internal surfaces of the conduits are minimized.

The first half convolution of conduit 9 is perforated, with the size and number of the perforations predetermined as hereinafter described, while the rest of conduit 9 is imperforate. At least the first several convolutions of conduit 10 adjacent the input end 16 thereof are uniformly perforated, with the size and number of perforations being adequate to allow all of the liquid contained in the convolutions to escape into the trough afforded by that portion of drum 11 which, at any particular time, is downwardly located. Liquid receiver 4 is provided to accommodate both the liquid escaping from the first half convolution of conduit 9 and the liquid escaping from conduit 10 and directed to the receiver by the drum.

As seenin FIGS. 2 and 4, receiver 4 is formed by walls 60 and 61 which extend transversely of the apparatus and are spaced longitudinally thereof, and cooperating side walls 62. The upper edges of walls 60 and 61 are generally arcuate and concave, with a radius of curvature significantly larger than the outer surface of thickened portion 19 of the drum ll. Walls 60-62 taper downwardly and are curved so as to have a lower cross-sectional configuration which matches the upper end of an upright tube 63, tube 63 being attached to such lower portions of walls 60-62 in fluid-tight relation.

The upper, upright portion of wall 60 is provided with a mounting bracket 64 of such configuration as to engage over a bracket 65 secured rigidly to plate 34. A support arm 66 is secured to the middle plate 33 and carries a band clamp 67 which is clamped to conduit 63. The combination of brackets 64, 65, arm 66 and band clamp 67 supports receiver 4 in an upright position with its open top centered on the series of slots 20 on drum 11 when the drum is properly supported by the roller stand. Walls 60 and 61 are spaced axially of the apparatus by a distance significantly greater than the length of slots 20. Accordingly, all liquid draining through slots 20 gravitates directly into the receiver 4 and is conveyed downwardly therefrom via conduit 63. The upper edges of walls 60-62 are spaced from drum 11 by a distance adequate to allow the first full convolution of the helix of tube 9 freedom of movement without interference from the stationary receiver 4. The perforated first half convolution of conduit 9 therefore passes through a lowermost position which is immediately above receiver 4 each time drum 11 completes one revolution. Accordingly, such liquid as is allowed to escape from conduit 9 via the perforations in the first half convolution thereof gravitates directly into receiver 4 and is conveyed downwardly via conduit 63. Conduit 63 is connected directly to the filter 5, FIG. 1, of the recycle system.

Pump 7 is operated continuously at a predetermined rate to deliver clarified liquid from centrifuge a, supplemented by fresh make-up liquid from tank 6, to the retaining tank 70 of feeding means 1. The material to be rehydrated is supplied to tank 70 at a predetermined rate, as hereinafter described, and is maintained uniformly suspended in the liquid, as by agitation as a result of the liquid inflow. Adjacent retaining tank 70 is a feed tank 71, the two tanks being connected via a weir 72. Feed tank 71 has a bottomvoutlet connected to a stationary conduit 73 which curves to extend horizontally in coaxial alignment with the input end of conduit 9, conduit 73 being connected to the input end 0 conduit 9 by swivel coupling 74.

As will be clear from FIGS. 9 and 9A, rotation of unit 2, as a result of operation of motor 52, through a substantial portion of each revolution causes the first half convolution 9' of conduit 9 to pass through positions, such as that seen in FIG. 9, in which that half convolution is effectively above that level of liquid in feed tank 71 which is established as the full condition for the feed tank. Accordingly, during this portion of each revolution of unit 2, liquid cannot flow through conduit 73 into conduit 9. As the first half convolution 9' of conduit 9 swings into its lower arc, however, the position thereof descends first below the liquid level in tank 71 and, ultimately, below the bottom outlet of the feed tank. As a result of such movement of the first half convolution 9', the entire contents of feed tank 71 drain through conduit 73 into the first half-convolution 9, as illustrated in FIG. 9A. Thus, in effect, feed tank 71 is dumped into the first half convolution of conduit 9 once during each revolution of the unit 2.

The rate of inflow of liquid into retaining tank 70, coupled with the rate of feed of the material to be rehydrated, is made such that a flow rate over weir 72 is established which will fill feed tank 71 during that portion of each revolution of unit 2 during which the first half convolution 9 is above those positions which will allow liquid to flow from the feed tank. In order to assure positive transfer of the material to be rehydrated, the total volume of material delivered to tank 71 via weir 72 during each revolution of unit 2 is made substantially greater than the effective volume of the first half convolution 9 of the conduit, the excess liquid escaping, via the perforations in the first half convolution 9', directly into the liquid receiver 4. In this connection, the size and number of the perforations in half convolution 9 are made such, in view of the speed of rotation of unit 2 and the amount of the excess liquid involved, that the excess liquid will escape via the perforations in the time required for the half convolution 9' to traverse one half revolution.

The combination of feed means 1 and unit 2 thus serves, first, to introduce automatically through the input end of conduit 9 a quantity of rehydration liquid and dried material, that quantity (after draining of excess liquid via the perforations in the first half convolution of conduit 9) being such as will be accommodated by any half convolution of conduit 9, and, second, to advance such quantities continuously to the end of conduit 9 and discharge them into conduit 10. The combination of conduits 9 and 10 functions as a helical pump, so that each quantity of rehydration liquid and dried material remaining after drainage in the first half convolution of conduit 9 advances one convolution during each revolution of unit 2, the quantities residing in the lower portions of the respective convolutions, generally in the fashion seen in FIG. 10, as the unit 2 rotates. When any quantity of liquid and dried material reaches the last convolution of conduit 9, the next revolution of unit 2 transfers that quantity into the first convolution of conduit 10, in the manner illustrated in FIGS. 10-10C. Since at least the first several convolutions of conduit 10 are perforated, the free rehydration liquid of each quantity passing from conduit 9 into conduit 10 drains promptly from conduit 10 into the effective trough presented by drum 1 1 below the helix of conduit 10. Since the helix of conduit 10 is wound oppositely with respect to that of conduit 9, rotation of unit 2 in a direction causing conduit 9 to advance the liquid and dried material from left to right, as viewed in FIG. 1, causes conduit 10 to advance any material delivered thereto from right to left, as viewed. Accordingly, the quantities delivered into conduit 10 advance with the first several convolutions of conduit 10, the liquid escaping through the perforations in those convolutions, and the solids continuing to advance with the remaining convolutions until discharged from end portion 18 of conduit 10 into off-bearing conveyor 3.

Liquid escaping via the perforations in conduit 10 falls into the trough afforded by the durm 11 and, due to the angle of inclination a, FIG. 1, of drum 11, flows along the inner surface of the drum until it reaches the slots 20. The liquid escapes through slots 20 directly into receiver 4 and is recycled via centrifuges 5, 5a, make-up tank 6, pump 7 and heat exchanger 8.

Though dried material can be supplied to feeding means 1 in any suitable fashion, it is advantageous to supply evacuated dried material in such manner that the dried material is immersed in the liquid in retaining tank without having been first exposed to the atmosphere. Such feeding of the material while still evacuated can be accomplished by the machanism shown in FIG. 11. The retaining tankj70 is provided with a screen 75 formed of a material of lower density than that of the rehydration liquid, the size and plan configuration of screen 75 being such that the screen is guided between a lower position, at the bottom of tank 70, and a raised position, determined by horizontal pins 76 projecting inwardly from the walls of tank 70 in a horizontal plane just below the level of weir 72. This guiding action results from sliding engagement of the edges of screen 75 and the walls of tank 70. Pins 76 lie in a common plane which is inclined downwardly toward weir 75 at a relatively small angle, e.g., 3-l0.

Mounted immedaitely adjacent tank 70 is a bag manipulator indicated generally at 77 and comprising a vertical rod 78 and a support member 79, the latter slidably engaging rod 78 andbeing provided with a handle 80. Member 79 carries a vertically dependent bar 81 to which are secured an upper clamp member 82 and a lower clamp member 83. Members 82, 83 are constructed to clamp and positively retain the respective opposite end portions of a flexible sealed bag 84 in which a quantity of the dried material has been packed under vacuum. The length of rod 78 is such that member 79 can be moved between an upper position, in which lower clamp member 83 is above the level of weir 72, and a lower position, seen in FIG. 11, in which thebag 84 is completely submerged in the liquid in tank 70.

Lower clamp member 83 carries a knife member 85 which is pivotally mounted, as by a pivot pin 86, to swing horizontally over the upper face of the clamp member. A bell crank member 87, mounted on member 83, has one of its lever arms connected to knife member 85 by a link 88, the other lever arm of bell crank 87 being connected to a vertical pull rod 89 extending along and slidably mounted on bar 81. Bell crank 87 is mounted to pivot about a horizontal axis. Pivot pin 86 is positioned near the end of knife member 85 to which link 88 is connected. The dispositions of the arms of bell crank 87 are such that, when rod 89 is pulled upwardly, knife member 85 is swung across member 83 to completely sever the walls of bag 84 immediately adjacent member 83.

Bag 84 is conventionally sealed, with the sealed end portions completely embraced by the respective clamp members 82, 83. Accordingly, when knife member 85 severs the bag, the rehydration liquid is free to enter the bag and the material contained within the bag is free to escape, with the liquid, into tank 70. Upward removal of the severed bag, by raising member 79, leaves the dried material in the liquid in tank 70. Insertion of rod 89 downwardly into tank 70 causes clamp member 83 to engage screen 75 and force the same to its lower Position. Hence, once the bag 84 has been opened and withdrawn, the dried material is left above the screen 75 and the screen accordingly, tending to return buoyantly to its uppermost position, urges the dried material toward the top of tank 70.

TYPICAL OPERATION OF THE APPARATUS OF ,FIGS. 1-12 The embodiment of the apparatus just described is expecially useful for rehydrating freeze dried shrimp. In a typical installation, the conduit 9 is employed to accomplish saturation of the freeze dried shrimp with an aqueous liquid rehydration medium and may have a cross-sectional inner diameter of, e.g., 6 in. and be arranged in a helix with a convolution mean diameter of, e.g., 6 ft. With the shrimp vacuum packed in bags each containing approximately 25 lbs. of dried shrimp, feed means 1 can be constructed to provide feed tank 71 with an effective capacity of 2.1 cu. ft. Unit 2 can be rotated at a speed of one revolution every 2 minutes, with the helix of outer conduit 9 having 13 turns and that of inner conduit 10having 35 turns, so that each quantity of rehydrating liquid and shrimp delivered by feed means 1 requires 26 minutes to traverse conduit 9, with the shrimp then requiring minutes to traverse conduit 10.

Water is employed as the rehydration liquid, with heat exchanger 8 operated to maintain the water at 40F. The apparatus of FIG. 11 is operated to empty two of the bags 84 into retaining tank 70 during that portion of each revolution of unit 2 during which the water in feed means 1 rises to the maximum level indicated at L, FIGS. 1 and 12, determined by the uppermost position reached by the first half convolution of conduit 9. As a result of the action of buoyant screen 75, all of the shrimp thus introduced are presented at and above the level of weir 72 by the time that the first half convolution of conduit 9 commences its downward travel, at which time the contents of feed tank 71, plus the liquid above weir 72, starts to flow through conduit 73. As the first half convolution of conduit 9 progresses downwardly and reaches its lowermost position, as seen in FIG. 12, the water in tank 71 and above weir 72 flows through conduit 73 and inlet portion 12 in to the first half convolution of FIG. 9. Water in excess of the desired quantity to be retained in each convolution of tube 9 drains through the perforations in the first half convolution, falling directly into receiver 4, the size and number of the perforations being selected to allow escape of the necessary quantity of water during that period of time required for the perforated portion to traverse the lower portion of its circular path. The result of each such cycle of operation of feeding means 1 is thus to supply to the conduit 9 a predetermined volume of water containing 50 lbs. of dried shrimp. The volume ratio of water to shrimp in the quantity established'for each convolution of conduit 9 is at least 1:1. The corresponding ratio in feed means 1 (considering only the water in tank 71 and above weir 74) is substantially greater than 1:1 due to the volume of water discharged via the perforations in the first half convolution of conduit 9.

As unit 2 continues to rotate, the quantity of water and shrimp in the first half convolution of conduit 9 progresses along the conduit at the rate of one convolution each revolution. During its residence in conduit 9, each such quantity retains its identity, being always present in the lower portion, typically the lower third, of one of the convolutions of the conduit. The continuous slow rotation of the helical conduit causes mild agitation of the water, and gentle tumbling of the shrimp, so that maximum effective contact of the water wit the shrimp is achieved.

Conduit 9 can be considered as defining an elongated rehydration zone through which each quantity of water and shrimp is passed at a controlled rate. When the evacuated dried shrimp is first exposed to the water in tank 70, a major portion of the water required to saturate the shrimp is promptly absorbed by the shrimp, so

that a substantial part of the initial stage of rehydration actually occurs before the shrimp enters conduit 9. The residence time of the shrimp in conduit 9 is chosen to assure that essentially complete saturation of the shrimp will have been accomplished by the time the shrimp enters conduit 10.

When each quantity of water and shrimp is discharged from outer conduit 9 into inner conduit 10, the

' free water remaining drains from conduit 10 and flows along the trough defined by drum 11, discharging via slots 20 into receiver 4. For each quantity, only the now saturated shrimp is retained by the conduit 10, and the shrimp is advanced, convolution-to-convolution, until it reaches the discharge end of conduit 10 and is deposited on conveyor 3. In this embodiment, the greater number of turns of the helix of conduit 10 assures that,

before being discharged onto the conveyor, the saturated shrimp will have had adequate time for equiibration of occur. Thus, conduit 10 can be considered as defining a dewatering zone, constituted bythe preforated first convolutions, and an equilibration zone, constituted by the remaining convolutions. The shrimp is presented on conveyor 3 in a condition closely approximating that which existed at the time the shrimp was freeze dried.

Though the mechanical action of conduits 9 and 10 on the shrimp is gentle, the liquid delivered to receiver 4, and hence to centrifuges and 5a, contains shrimp fragments of sufficient value to warrant recovery. Such fragments are separated from the recycle water by centrifuges 5, 5a, and removed in the form of moist solids ready for processing into, e.g., shrimp cakes.

The clarified water, with fresh make-up water from tank 6, is delivered back to tank 70 via pump 7 and heat exchanger 8.

ALTERNATIVE EMBODIMENTS The apparatus is advantageously provided with means for subjecting the material in the dewatering zone to sonic energy at relatively low frequency. Accordingly, as seen in FIG. 13, one or more couplings 95 are provided in the perforated first convolutions of conduit 10, each coupling 95 carrying at least one sonic energy generator 96. Generator 96 has a sonic energy transmission face 97 which is arcuate and so disposed as to constitute an extension of the inner surface of conduit 10. When, as in FIG. 13, only one sonic generator 96 is employed, the generator is located in an outer wall portion of the conduit, so as to be below the contents of the convolution of the conduit as that portion of the conduit passes through the lower portion of its travel, so that better contact between the contents and face 97 is achieved. The effect of sonic generator 96 is to impart sonic energy to the shrimp during dewatering, and preferably just after the bulk of the free liquid has drained from tube 10, to accomplish a more complete removal of free water from the shrimp so that, on leaving the dewatering zone, the shrimp carries only the absorbed water which, after equilibration, will approximate the water contained by the shrimp when fresh.

Sonic generators as shown in FIG. 13 can also be provided at spaced points along conduit 9, in which case the sonic generator is selected to provide sonic energy at a higher frequency, in order to sonically vibrate the shrimp, during rehydration, at a frequency which will aid the escape of gas from the shrimp.

To provide optimum rehydration, it is particularly advantageous to provide the apparatus with means whereby at least one intermediate convolution of conduit 9 can be placed under a markedly'reduced pressure. This can be accomplished in the manner shown in FIG. 14, with a cross tube connected to communiquantity of rehydration liquid and material to be rehydrated is to be held at the reduced pressure for a period longer than one revolution of the unit 2. Since the air introduced in the first or input convolution of conduit 9 is at atmospheric pressure, while vacuum line 104 and cross tube 100 will typically provide a vacuum of, e.g., 20 in. Hg in the convolution with which tube 100 communicates, the latter convolution should be spaced from the input end of conduit 9 by a substantial number of convolutions to allow progressive convolution-toconvolution reduction in pressure, and should also be spaced from the output end of the conduit by a substantial number of convolutions to allow gradual, convolution-to-convolution return to atmospheric pressure.

The effect of placing one or more of the convolutions of condiut 9 under a markedly reduced pressure is to essentially fully de-gas the shrimp while the shrimp is immersed in the liquid rehydration medium. When the shrimp immersed in the liquid in feed means 1 is vacuum packed, this de-gassing action removes those small quantities of gas present even in the vacuum packed product. When the shrimp has not been previously evacuated, as by vacuum packing, the reduced pressure established in one or more convolutions of conduit 9 removes large quantities of gas from the shrimp. In both cases, de-gassing causes the structure of the shrimp to flex in the presence of the rehydrating liquid and effectively aids rehydration.

While it is particularly advantageous to employ, for conduits 9 and 10, extruded polymeric pipe of such flexibility as to allow the pipe to be readily coiled into and unwound from the helical configurations shown, other types of conduits can be employed. Thus, as shown in FIG. 15, conduits of rectangular cross section can be provided, as by helically winding an extruded strip of polymeric material which is of L-shaped transverse cross section, with one flange 111 of the L- shaped cross section lying in a cylindrical plane concentric with drum 11 and the other flange 112 thereof lying in a helically extending plane transverse to the drum.

The embodiment of FIGS. 1-12 is advantageous in that the concentric and reverse disposition of the helices of conduits 9 and 10 affords a maximum product residence time in an apparatus of minimum length. As illustrated in FIG. 16, however, the two conduits can extend in the same direction and along the same surface of the drum when relatively shorter residence times are desired. Thus, drum 211 is elongated, with conduit 209 extending helically about a first portion of the drum, and conduit 210 extending in the same helical fashion about the remaining portion of the drum. A single liquid receiving trough 204 extends beneath the drum 211 for somewhat more than the full length of the combined helices, the bottom wall of trough 204 being inclined downwardly toward one end so that the liquid discharged from the first half convolution of conduit 209 and from conduit 210 can be recycled to the feed means 201 as hereinbefore described.

What is claimed is:

1. In an apparatus for continuous rehydration of dried material, the combination of elongated conduit means comprising a first generally helically extending portion and a second generally helicallyextending portion,

said-first portion defininga rehydration zone,

said second portion defining a dewatering zone,

said first and second portions each having an inlet end and a discharge end and being arranged with the discharge end of said first portion connected to the input end of said second portion; support means supporting said conduit means'for rotation about a generally horizontally axis, the helical convolutions of said first and second-portions being concentric with said axis; drive means connected to rotate the combination of said support means and said conduit means continuously at a slow rate; reservoir means for containing an aqueous liquid rehydration medium in which the material to be rehydrated is immersed; and cyclic feed means connected to the input end'of said first conduit portion and communicating with said reservoir means, said cyclic feed means being operative to supply from the reservoir means to the input end of said first conduit portion a predetermined volume of the aqueous liquid rehydration medium and material to be rehydrated, during each revolution of the combination of said support means and said conduit means, which volume is significantly less than that requiredto fill the first convolution of the helix of said first portion of said conduit means; said second portion of said conduit means being provided with openings via which excess liquid can escape therefrom. v

2. The combination defined in claim 1 and further comprising Y J I means for collecting liquid from said conduit means and recycling the collected liquid to said cyclic feed means. i 3. The combination defined in claim 1, wherein the-diameters of the helices of said first and second conduit portions are unequal,

the helix formed by one of said conduit portions being surrounded by the helix of the other of said conduit portions, and said helices extending in opposite directions.

4. The combination defined in claim 3, wherein the helix of said second conduit portion is surrounded by the helix of said first conduit portion.

5. The combination defined in claim 4, wherein said support means comprises a hollow elongated cylindrical member,

the helix of said first conduit portion is located outside of said cylindrical member, and

the helix of said second conduit portion extends within said cylindrical member.

6. The combination defined in claim 5, wherein the longitudinal axis of said cylindrical member is coincident with the central axis of the helices of said conduit portions and is disposed at a small angle of inclination relative to the horizontal, whereby liquid escaping from said second conduit portion is conducted to a discharge point by said cylindrical member. 7. The combination defined in claim 6, wherein the interconnected discharge end of said first conduit portion and input end of said second conduit portion are located adjacent one end of said cylindrical member, a said discharge point is located at the other end of said cylindrical member, and the longitudinal axis of said cylindrical member slants downwardly from said one end of said cylindrical member, the liquid escaping from said second conduit flowing by gravity along the wall of said cylindrical member. 8. The combination defined in claim 7, wherein the convolutions of said second conduit portion are spaced inwardly from the wall of said cylindrical member. 9. The combination defined in claim 5, wherein the discharge end of said first conduit portion and the input end of said second conduit portion are releasably interconnected, the combination further comprising internal frame means on which the helix of said second conduit portion is supported, the combination of said frame means and said second conduit portion being removable axially from said cylindrical member after the input end of said second conduit portion has been released from the discharge end of said first conduit portion. 10. The combination defined in claim 9, wherein the outer diameter of the helix of said second conduit portion is smaller than the inner diameter of said cylindrical member, and said frame means comprises outwardly extending spacer elements dimensioned and disposed to engage saidcylindrical member, Y the convolutions of the helix of said second conduit portion being spaced inwardly from the wall of I said cylindrical member by reason of said spacer elements. a 11. The combination defined in claim 1, wherein said first and second conduit portions are of polymeric material of sufficient flexibility to be straightened for cleaning when removed from said support means. 12. in an apparatus for continuous rehydration of dried material, the combination of elongated conduit means comprising a first generally helically extending portion and a second generally helically extending portion, said first portion defining a-rehydration zone and having an input end located generally at the longitudinal axis of the helix of said first portion, said second portion defining a dewatering zone and being provided with openings via which excess "liquid can escape therefrom, said first and second portions each having an inlet end and a discharge end and being arranged with the discharge end of said first portion connected to the input end of said second portion; support means supporting said conduit means for rotation about a generally horizontal axis,

the helical convolutions of said first and second portions being concentric with said axis; drive means connected to rotate the combination of said support means and said conduit means continuously at a slow rate; and

cyclic feed means comprising a container having a drain communicating with said inlet end of said first portion of said conduit means, said'container being arranged to retain a substantial body of liquid whenever the first half convolution of said first portion of said conduit means is in an upper portion of its travel during rotation of said conduit means, and

means for delivering liquid to said feed means means for collecting liquid from said conduit means and recycling the collected liquid to said means for continuously delivering liquid to said feed means. 14. The combination defined in claim 12, wherein said container comprises first and second liquid-confining portions, a weir operatively arranged between said first and second liquid-confining portions to allow liquid to flow from said first portion to said second portion, and confining walls located above said weir defining a liquid retaining portion communicating with both said first and second liquid-confining portions, said'rneans for continuously delivering liquid being connected to deliver liquid to said first liquidconfining portion, and said drain communicating between said second liquid-confining portion and said inlet end of said first portion of said conduit means. 

1. In an apparatus for continuous rehydration of dried material, the combination of elongated conduit means comprising a first generally helically extending portion and a second generally helically extending portion, said first portion defining a rehydration zone, said second portion defining a dewatering zone, said first and second portions each having an inlet end and a discharge end and being arranged with the discharge end of said first portion connected to the input end of said second portion; support means supporting said conduit means for rotation about a generally horizontally axis, the helical convolutions of said first and second portions being concentric with said axis; drive means connected to rotate the combination of said support means and said conduit means continuously at a slow rate; reservoir means for containing an aqueous liquid rehydration medium in which the material to be rehydrated is immersed; and cyclic feed means connected to the input end of said first conduit portion and communicating with said reservoir means, said cyclic feed means being operative to supply from the reservoir means to the input end of said fiRst conduit portion a predetermined volume of the aqueous liquid rehydration medium and material to be rehydrated, during each revolution of the combination of said support means and said conduit means, which volume is significantly less than that required to fill the first convolution of the helix of said first portion of said conduit means; said second portion of said conduit means being provided with openings via which excess liquid can escape therefrom.
 2. The combination defined in claim 1 and further comprising means for collecting liquid from said conduit means and recycling the collected liquid to said cyclic feed means.
 3. The combination defined in claim 1, wherein the diameters of the helices of said first and second conduit portions are unequal, the helix formed by one of said conduit portions being surrounded by the helix of the other of said conduit portions, and said helices extending in opposite directions.
 4. The combination defined in claim 3, wherein the helix of said second conduit portion is surrounded by the helix of said first conduit portion.
 5. The combination defined in claim 4, wherein said support means comprises a hollow elongated cylindrical member, the helix of said first conduit portion is located outside of said cylindrical member, and the helix of said second conduit portion extends within said cylindrical member.
 6. The combination defined in claim 5, wherein the longitudinal axis of said cylindrical member is coincident with the central axis of the helices of said conduit portions and is disposed at a small angle of inclination relative to the horizontal, whereby liquid escaping from said second conduit portion is conducted to a discharge point by said cylindrical member.
 7. The combination defined in claim 6, wherein the interconnected discharge end of said first conduit portion and input end of said second conduit portion are located adjacent one end of said cylindrical member, said discharge point is located at the other end of said cylindrical member, and the longitudinal axis of said cylindrical member slants downwardly from said one end of said cylindrical member, the liquid escaping from said second conduit flowing by gravity along the wall of said cylindrical member.
 8. The combination defined in claim 7, wherein the convolutions of said second conduit portion are spaced inwardly from the wall of said cylindrical member.
 9. The combination defined in claim 5, wherein the discharge end of said first conduit portion and the input end of said second conduit portion are releasably interconnected, the combination further comprising internal frame means on which the helix of said second conduit portion is supported, the combination of said frame means and said second conduit portion being removable axially from said cylindrical member after the input end of said second conduit portion has been released from the discharge end of said first conduit portion.
 10. The combination defined in claim 9, wherein the outer diameter of the helix of said second conduit portion is smaller than the inner diameter of said cylindrical member, and said frame means comprises outwardly extending spacer elements dimensioned and disposed to engage said cylindrical member, the convolutions of the helix of said second conduit portion being spaced inwardly from the wall of said cylindrical member by reason of said spacer elements.
 11. The combination defined in claim 1, wherein said first and second conduit portions are of polymeric material of sufficient flexibility to be straightened for cleaning when removed from said support means.
 12. In an apparatus for continuous rehydration of dried material, the combination of elongated conduit means comprising a first generally helically extending portion and a second generally helically extending portion, said first portion defining a rehydration zone and having aN input end located generally at the longitudinal axis of the helix of said first portion, said second portion defining a dewatering zone and being provided with openings via which excess liquid can escape therefrom, said first and second portions each having an inlet end and a discharge end and being arranged with the discharge end of said first portion connected to the input end of said second portion; support means supporting said conduit means for rotation about a generally horizontal axis, the helical convolutions of said first and second portions being concentric with said axis; drive means connected to rotate the combination of said support means and said conduit means continuously at a slow rate; and cyclic feed means comprising a container having a drain communicating with said inlet end of said first portion of said conduit means, said container being arranged to retain a substantial body of liquid whenever the first half convolution of said first portion of said conduit means is in an upper portion of its travel during rotation of said conduit means, and means for delivering liquid to said feed means while said conduit means is rotating, movement of the first half convolution of said first portion of said conduit means into a lower portion of its travel during rotation thereof causing liquid to drain into said first half convolution.
 13. The combination defined in claim 12 and further comprising means for collecting liquid from said conduit means and recycling the collected liquid to said means for continuously delivering liquid to said feed means.
 14. The combination defined in claim 12, wherein said container comprises first and second liquid-confining portions, a weir operatively arranged between said first and second liquid-confining portions to allow liquid to flow from said first portion to said second portion, and confining walls located above said weir defining a liquid retaining portion communicating with both said first and second liquid-confining portions, said means for continuously delivering liquid being connected to deliver liquid to said first liquid-confining portion, and said drain communicating between said second liquid-confining portion and said inlet end of said first portion of said conduit means. 